Object direction mechanism for turbofan engine

ABSTRACT

A turbofan engine is provided. The turbofan engine includes a fan comprising a plurality of fan blades; a turbomachine operably coupled to the fan for driving the fan, the turbomachine comprising a compressor section, a combustion section, and a turbine section in serial flow order and together defining a core air flowpath; a nacelle surrounding and at least partially enclosing the fan; an inlet pre-swirl feature located upstream of the plurality of fan blades, the inlet pre-swirl feature attached to or integrated into the nacelle; and a means for directing incoming objects towards an outer portion of the turbofan engine in communication with the inlet pre-swirl feature.

TECHNICAL FIELD

The present subject matter relates generally to a gas turbine engine, ormore particularly to a gas turbine engine configured to direct incomingobjects towards an outer portion of the engine and away from a core ofthe engine.

BACKGROUND

A turbofan engine generally includes a fan having a plurality of fanblades and a turbomachine arranged in flow communication with oneanother. Additionally, the turbomachine of the turbofan engine generallyincludes, in serial flow order, a compressor section, a combustionsection, a turbine section, and an exhaust section. In operation, air isprovided from the fan to an inlet of the compressor section where one ormore axial compressors progressively compress the air until it reachesthe combustion section. Fuel is mixed with the compressed air and burnedwithin the combustion section to provide combustion gases. Thecombustion gases are routed from the combustion section to the turbinesection. The flow of combustion gasses through the turbine sectiondrives the turbine section and is then routed through the exhaustsection, e.g., to atmosphere.

However, during flight, foreign objects in the sky may enter into a coreof the engine. The inventors of the present disclosure have found thatit may be beneficial to include one or more features to direct theseforeign objects towards an outer portion of the engine, away from theinlet of the compressor section.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present disclosure, including thebest mode thereof, directed to one of ordinary skill in the art, is setforth in the specification, which makes reference to the appendedfigures, in which:

FIG. 1 is a schematic cross-sectional view of an exemplary gas turbineengine according to an exemplary embodiment of the present subjectmatter.

FIG. 2 is a close-up, schematic, cross-sectional view of a forward endof the exemplary gas turbine engine of FIG. 1 according to an exemplaryembodiment of the present subject matter.

FIG. 3 is a schematic view of an inlet to the exemplary gas turbineengine of FIG. 1 , along an axial direction of the gas turbine engine ofFIG. 1 according to an exemplary embodiment of the present subjectmatter.

FIG. 4 it is a schematic view of an inlet to a gas turbine engine inaccordance with another exemplary embodiment of the present disclosure.

FIG. 5 is a schematic cross-sectional view of an exemplary gas turbineengine according to an exemplary embodiment of the present subjectmatter.

FIG. 6 is a close-up, schematic, cross-sectional view of a forward endof the exemplary gas turbine engine of FIG. 1 according to anotherexemplary embodiment of the present subject matter.

FIG. 7 is a schematic cross-sectional view of an exemplary gas turbineengine according to another exemplary embodiment of the present subjectmatter.

FIG. 8 is a schematic cross-sectional view of an exemplary gas turbineengine according to another exemplary embodiment of the present subjectmatter.

FIG. 9 is a schematic cross-sectional view of an exemplary gas turbineengine according to another exemplary embodiment of the present subjectmatter.

FIG. 10 is a schematic cross-sectional view of an exemplary gas turbineengine according to another exemplary embodiment of the present subjectmatter.

Corresponding reference characters indicate corresponding partsthroughout the several views. The exemplifications set out hereinillustrate exemplary embodiments of the disclosure, and suchexemplifications are not to be construed as limiting the scope of thedisclosure in any manner.

DETAILED DESCRIPTION

Reference will now be made in detail to present embodiments of thedisclosure, one or more examples of which are illustrated in theaccompanying drawings. The detailed description uses numerical andletter designations to refer to features in the drawings. Like orsimilar designations in the drawings and description have been used torefer to like or similar parts of the disclosure.

The following description is provided to enable those skilled in the artto make and use the described embodiments contemplated for carrying outthe disclosure. Various modifications, equivalents, variations, andalternatives, however, will remain readily apparent to those skilled inthe art. Any and all such modifications, variations, equivalents, andalternatives are intended to fall within the scope of the presentdisclosure.

The word “exemplary” is used herein to mean “serving as an example,instance, or illustration.” Any implementation described herein as“exemplary” is not necessarily to be construed as preferred oradvantageous over other implementations. Additionally, unlessspecifically identified otherwise, all embodiments described hereinshould be considered exemplary.

For purposes of the description hereinafter, the terms “upper”, “lower”,“right”, “left”, “vertical”, “horizontal”, “top”, “bottom”, “lateral”,“longitudinal”, and derivatives thereof shall relate to the disclosureas it is oriented in the drawing figures. However, it is to beunderstood that the disclosure may assume various alternativevariations, except where expressly specified to the contrary. It is alsoto be understood that the specific devices illustrated in the attacheddrawings, and described in the following specification, are simplyexemplary embodiments of the disclosure. Hence, specific dimensions andother physical characteristics related to the embodiments disclosedherein are not to be considered as limiting.

As used herein, the terms “first”, “second”, and “third” may be usedinterchangeably to distinguish one component from another and are notintended to signify location or importance of the individual components.

The terms “forward” and “aft” refer to relative positions within a gasturbine engine, with forward referring to a position closer to an engineinlet and aft referring to a position closer to an engine nozzle orexhaust.

The terms “upstream” and “downstream” refer to the relative directionwith respect to fluid flow in a fluid pathway. For example, “upstream”refers to the direction from which the fluid flows, and “downstream”refers to the direction to which the fluid flows.

The singular forms “a”, “an”, and “the” include plural references unlessthe context clearly dictates otherwise.

Additionally, the terms “low,” “high,” or their respective comparativedegrees (e.g., lower, higher, where applicable) each refer to relativespeeds or pressures within an engine, unless otherwise specified. Forexample, a “low-pressure turbine” operates at a pressure generally lowerthan a “high-pressure turbine.” Alternatively, unless otherwisespecified, the aforementioned terms may be understood in theirsuperlative degree. For example, a “low-pressure turbine” may refer tothe lowest maximum pressure turbine within a turbine section, and a“high-pressure turbine” may refer to the highest maximum pressureturbine within the turbine section. An engine of the present disclosuremay also include an intermediate pressure turbine, e.g., an enginehaving three spools.

Approximating language, as used herein throughout the specification andclaims, is applied to modify any quantitative representation that couldpermissibly vary without resulting in a change in the basic function towhich it is related. Accordingly, a value modified by a term or terms,such as “about”, “approximately”, and “substantially”, are not to belimited to the precise value specified. In at least some instances, theapproximating language may correspond to the precision of an instrumentfor measuring the value, or the precision of the methods or machines forconstructing or manufacturing the components and/or systems. Forexample, the approximating language may refer to being within a 1, 2, 4,10, 15, or 20 percent margin. These approximating margins may apply to asingle value, either or both endpoints defining numerical ranges, and/orthe margin for ranges between endpoints.

Here and throughout the specification and claims, range limitations arecombined and interchanged, such ranges are identified and include allthe sub-ranges contained therein unless context or language indicatesotherwise. For example, all ranges disclosed herein are inclusive of theendpoints, and the endpoints are independently combinable with eachother.

As used herein, the term “fan pressure ratio” refers to a ratio of anair pressure immediately downstream of the fan blades if a fan duringoperation of the fan to an air pressure immediately upstream of the fanblades of the fan during operation of the fan.

As used herein, the term “rated speed” with reference to a turbofanengine refers to a maximum rotational speed that the turbofan engine mayachieve while operating properly. For example, the turbofan engine maybe operating at the rated speed during maximum load operations, such asduring takeoff operations.

Also as used herein, the term “fan tip speed” as defined by theplurality of fan blades of the fan refers to a linear speed of an outertip of a fan blade along a radial direction during operation of the fan.

The present disclosure is generally related to a means for directingincoming objects towards an outer portion of a turbofan engine incommunication with and/or on an inlet pre-swirl feature, e.g.,configured as a plurality of part span inlet guide vanes. The means fordirecting incoming objects towards the outer portion of the turbofanengine directs incoming objects away from a core air flowpath of theengine and towards a bypass airflow passage. This provides a deflectionmechanism that facilitates ingestion of an object into an outer portionof the engine by minimizing the chance that the object travels to thecore of the engine.

In some exemplary embodiments of the present disclosure, the means fordirecting incoming objects towards an outer portion of the turbofanengine includes a shroud in communication with a portion of the inletpre-swirl feature, e.g., configured as a plurality of part span inletguide vanes.

In other exemplary embodiments of the present disclosure, the means fordirecting incoming objects towards an outer portion of the turbofanengine includes a leading edge of the inlet pre-swirl feature, e.g.,configured as a plurality of part span inlet guide vanes, having aforward sweep angle.

In other exemplary embodiments of the present disclosure, the means fordirecting incoming objects towards an outer portion of the turbofanengine includes a leading edge of the inlet pre-swirl feature, e.g.,configured as a plurality of part span inlet guide vanes, that isserrated.

In other exemplary embodiments of the present disclosure, the means fordirecting incoming objects towards an outer portion of the turbofanengine includes an inlet pre-swirl feature, e.g., configured as aplurality of part span inlet guide vanes, having a leading edge formedof a metallic material. For example, the inlet pre-swirl feature, e.g.,configured as a plurality of part span inlet guide vanes, can be made ofmany different materials, including polymer composites made of carbonfiber & resin, or fabricated from metal, including aluminum or stainlesssteel alloys. A composite or aluminum pre-swirl feature may incorporatea metallic leading edge made of titanium or stainless steel specificallyto provide stiffness and address the issue of bird ingestion.Incorporating additional stiffness into the pre-swirl feature design viainternal trusses or other structures should be well known to one that isskilled in the art, and can be accomplished by many different structuralmethods, depending on the chosen material and blade shape.

Referring now to the drawings, wherein identical numerals indicate thesame elements throughout the figures, FIG. 1 is a schematiccross-sectional view of a gas turbine engine in accordance with anexemplary embodiment of the present disclosure. More particularly, forthe embodiment of FIG. 1 , the gas turbine engine is an aeronautical,turbofan jet engine 10, referred to herein as “turbofan engine 10”,configured to be mounted to an aircraft, such as in an under-wingconfiguration or tail-mounted configuration. As shown in FIG. 1 , theturbofan engine 10 defines an axial direction A (extending parallel to alongitudinal centerline 12 provided for reference), a radial directionR, and a circumferential direction (i.e., a direction extending aboutthe axial direction A; not depicted). In general, the turbofan engine 10includes a fan section 14 and a turbomachine 16 disposed downstream fromthe fan section 14 (the turbomachine 16 sometimes also, oralternatively, referred to as a “core turbine engine”).

The exemplary turbomachine 16 depicted generally includes asubstantially tubular outer casing 18 that defines an annular inlet 20.The outer casing 18 encases, in serial flow relationship, a compressorsection including a first, booster or low pressure (LP) compressor 22and a second, high pressure (HP) compressor 24; a combustion section 26;a turbine section including a first, high pressure (HP) turbine 28 and asecond, low pressure (LP) turbine 30; and a jet exhaust nozzle section32. A high pressure (HP) shaft 34 drivingly connects the HP turbine 28to the HP compressor 24. A low pressure (LP) shaft 36 drivingly connectsthe LP turbine 30 to the LP compressor 22. The compressor section,combustion section 26, turbine section, and jet exhaust nozzle section32 are arranged in serial flow order and together define a core airflowpath 37 through the turbomachine 16. It is also contemplated thatthe present disclosure is compatible with an engine having anintermediate pressure turbine, e.g., an engine having three spools.

Referring still the embodiment of FIG. 1 , the fan section 14 includes avariable pitch, single stage fan 38, the turbomachine 16 operablycoupled to the fan 38 for driving the fan 38. The fan 38 includes aplurality of rotatable fan blades 40 coupled to a disk 42 in a spacedapart manner. As depicted, the fan blades 40 extend outwardly from disk42 generally along the radial direction R. Each fan blade 40 isrotatable relative to the disk 42 about a pitch axis P by virtue of thefan blades 40 being operatively coupled to a suitable actuation member44 configured to collectively vary the pitch of the fan blades 40, e.g.,in unison. The fan blades 40, disk 42, and actuation member 44 aretogether rotatable about the longitudinal centerline 12 by LP shaft 36across a power gear box 46. The power gear box 46 includes a pluralityof gears for stepping down the rotational speed of the LP shaft 36 to amore efficient rotational fan speed. Accordingly, for the embodimentdepicted, the turbomachine 16 is operably coupled to the fan 38 throughthe power gear box 46.

In exemplary embodiments, the fan section 14 includes twenty-two (22) orfewer fan blades 40. In certain exemplary embodiments, the fan section14 includes twenty (20) or fewer fan blades 40. In certain exemplaryembodiments, the fan section 14 includes eighteen (18) or fewer fanblades 40. In certain exemplary embodiments, the fan section 14 includessixteen (16) or fewer fan blades 40. In certain exemplary embodiments,it is contemplated that the fan section 14 includes other number of fanblades 40 for a particular application.

During operation of the turbofan engine 10, the fan 38 defines a fanpressure ratio and the plurality of fan blades 40 each define a fan tipspeed. The exemplary turbofan engine 10 depicted defines a relativelyhigh fan tip speed and relatively low fan pressure ratio duringoperation of the turbofan engine at a rated speed. As used herein, theterm “fan pressure ratio” refers to a ratio of an air pressureimmediately downstream of the fan blades 40 during operation of the fan38 to an air pressure immediately upstream of the fan blades 40 duringoperation of the fan 38. For the embodiment depicted in FIG. 1 , the fan38 of the turbofan engine 10 defines a relatively low fan pressureratio. For example, the turbofan engine 10 depicted defines a fanpressure ratio less than or equal to about 1.5. For example, in certainexemplary embodiments, the turbofan engine 10 may define a fan pressureratio less than or equal to about 1.4. The fan pressure ratio may be thefan pressure ratio of the fan 38 during operation of the turbofan engine10, such as during operation of the turbofan engine 10 at a rated speed.

As used herein, the term “rated speed” with reference to the turbofanengine 10 refers to a maximum rotational speed that the turbofan engine10 may achieve while operating properly. For example, the turbofanengine 10 may be operating at the rated speed during maximum loadoperations, such as during takeoff operations.

Also as used herein, the term “fan tip speed” defined by the pluralityof fan blades 40 refers to a linear speed of an outer tip of a fan blade40 along the radial direction R during operation of the fan 38. Inexemplary embodiments, the turbofan engine 10 of the present disclosurecauses the fan blades 40 of the fan 38 to rotate at a relatively highrotational speed. For example, during operation of the turbofan engine10 at the rated speed, the fan tip speed of each of the plurality of fanblades 40 is greater than or equal to 1000 feet per second and less thanor equal to 2250 feet per second. In certain exemplary embodiments,during operation of the turbofan engine 10 at the rated speed, the fantip speed of each of the fan blades 40 may be greater than or equal to1,250 feet per second and less than or equal to 2250 feet per second. Incertain exemplary embodiments, during operation of the turbofan engine10 at the rated speed, the fan tip speed of each of the fan blades 40may be greater than or equal to about 1,350 feet per second, such asgreater than about 1,450 feet per second, such as greater than about1,550 feet per second, and less than or equal to 2250 feet per second.

Referring still to the exemplary embodiment of FIG. 1 , the disk 42 iscovered by rotatable front nacelle or hub 48 aerodynamically contouredto promote an airflow through the plurality of fan blades 40.Additionally, the exemplary fan section 14 includes an annular fancasing or outer nacelle 50 that at least partially, and for theembodiment depicted, circumferentially, surrounds the fan 38 and atleast a portion of the turbomachine 16.

More specifically, the outer nacelle 50 includes an inner wall 52 and adownstream section 54 of the inner wall 52 of the outer nacelle 50extends over an outer portion of the turbomachine 16 so as to define abypass airflow passage 56 therebetween. Additionally, for the embodimentdepicted, the outer nacelle 50 is supported relative to the turbomachine16 by a plurality of circumferentially spaced outlet guide vanes 55.

During operation of the turbofan engine 10, a volume of air 58 entersthe turbofan engine 10 through an associated inlet 60 of the outernacelle 50 and/or fan section 14. As the volume of air 58 passes acrossthe fan blades 40, a first portion of the air 58 as indicated by arrows62 is directed or routed into the bypass airflow passage 56 and a secondportion of the air 58 as indicated by arrow 64 is directed or routedinto the core air flowpath 37. The ratio between an amount of airflowthrough the bypass airflow passage 56 (i.e., the first portion of airindicated by arrows 62) to an amount of airflow through the core airflowpath 37 (i.e., the second portion of air indicated by arrows 64) isknown as a bypass ratio.

In exemplary embodiments, the bypass ratio during operation of theturbofan engine 10 (e.g., at a rated speed) is less than or equal toabout eleven (11). For example, the bypass ratio during operation of theturbofan engine 10 (e.g., at a rated speed) may be less than or equal toabout ten (10), such as less than or equal to about nine (9).Additionally, the bypass ratio may be at least about two (2).

In other exemplary embodiments, the bypass ratio may generally bebetween about 7:1 and about 20:1, such as between about 10:1 and about18:1. The pressure of the second portion of air 64 is then increased asit is routed through the high pressure (HP) compressor 24 and into thecombustion section 26, where it is mixed with fuel and burned to providecombustion gases 66.

In exemplary embodiments, a gear ratio of the power gear box 46 isgreater than or equal to 1.2 and less than or equal to 3.0. In someexemplary embodiments, the gear ratio of the power gear box 46 isgreater than or equal to 1.2 and less than or equal to 2.6. In otherexemplary embodiments, the gear ratio of the power gear box 46 isgreater than or equal to 1.2 and less than or equal to 2.0.

Furthermore, the turbofan engine of the present disclosure also providespre-swirling flow forward of the fan blade tip as described herein.

Referring still to FIG. 1 , the compressed second portion of air 64 fromthe compressor section mixes with fuel and is burned within thecombustion section to provide combustion gases 66. The combustion gases66 are routed from the combustion section 26, through the HP turbine 28where a portion of thermal and/or kinetic energy from the combustiongases 66 is extracted via sequential stages of HP turbine stator vanes68 that are coupled to the outer casing 18 and HP turbine rotor blades70 that are coupled to the HP shaft 34, thus causing the HP shaft 34 torotate, thereby supporting operation of the HP compressor 24. Thecombustion gases 66 are then routed through the LP turbine 30 where asecond portion of thermal and kinetic energy is extracted from thecombustion gases 66 via sequential stages of LP turbine stator vanes 72that are coupled to the outer casing 18 and LP turbine rotor blades 74that are coupled to the LP shaft 36, thus causing the LP shaft 36 torotate, thereby supporting operation of the LP compressor 22 and/orrotation of the fan 38.

The combustion gases 66 are subsequently routed through the jet exhaustnozzle section 32 of the turbomachine 16 to provide propulsive thrust.Simultaneously, the pressure of the first portion of air 62 issubstantially increased as the first portion of air 62 is routed throughthe bypass airflow passage 56 before it is exhausted from a fan nozzleexhaust section 76 of the turbofan 10, also providing propulsive thrust.The HP turbine 28, the LP turbine 30, and the jet exhaust nozzle section32 at least partially define a hot gas path 78 for routing thecombustion gases 66 through the turbomachine 16.

Referring still to FIG. 1 , the turbofan engine 10 additionally includesa means for directing incoming objects towards an outer portion of theturbofan engine 200 in communication and/or on the inlet pre-swirlfeature, e.g., configured as a plurality of part span inlet guide vanes100, as described in greater detail herein. As described herein, themeans for directing incoming objects towards an outer portion of theturbofan engine 200 directs incoming objects away from the core airflowpath 37 and towards the bypass airflow passage 56.

In some exemplary embodiments, it will be appreciated that the exemplaryturbofan engine 10 of the present disclosure may be a relatively largepower class turbofan engine 10. Accordingly, when operated at the ratedspeed, the turbofan engine 10 may be configured to generate a relativelylarge amount of thrust. More specifically, when operated at the ratedspeed, the turbofan engine 10 may be configured to generate at leastabout 20,000 pounds of thrust, such as at least about 25,000 pounds ofthrust, such as at least about 30,000 pounds of thrust, and up to, e.g.,about 150,000 pounds of thrust. Accordingly, the turbofan engine 10 maybe referred to as a relatively large power class gas turbine engine.

Moreover, it should be appreciated that the exemplary turbofan engine 10depicted in FIG. 1 is by way of example only, and that in otherexemplary embodiments, the turbofan engine 10 may have any othersuitable configuration. For example, in certain exemplary embodiments,the fan may not be a variable pitch fan, the engine may not include areduction gearbox (e.g., power gearbox 46) driving the fan, may includeany other suitable number or arrangement of shafts, spools, compressors,turbines, etc.

As discussed above, the turbofan engine 10 of the present disclosurealso provides pre-swirling flow forward of the fan blade tip. Referringnow also to FIG. 2 , a close-up, cross-sectional view of the fan section14 and forward end of the turbomachine 16 of the exemplary turbofanengine 10 of FIG. 1 is provided. In exemplary embodiments, the turbofanengine 10 includes an inlet pre-swirl feature located upstream of theplurality of fan blades 40 of the fan 38 and attached to or integratedinto the outer nacelle 50. More specifically, for the embodiment ofFIGS. 1 and 2 , the inlet pre-swirl feature is configured as a pluralityof part span inlet guide vanes 100. The plurality of part span inletguide vanes 100 are each cantilevered from of the outer nacelle 50 (suchas from the inner wall 52 of the outer nacelle 50) at a location forwardof the plurality of fan blades 40 of the fan 38 along the axialdirection A and aft of the inlet 60 of the outer nacelle 50. Morespecifically, each of the plurality of part span inlet guide vanes 100define an outer end 102 along the radial direction R, and are attachedto/connected to the outer nacelle 50 at the radially outer end 102through a suitable connection means (not shown). For example, each ofthe plurality of part span inlet guide vanes 100 may be bolted to theinner wall 52 of the outer nacelle 50 at the outer end 102, welded tothe inner wall 52 of the outer nacelle 50 at the outer end 102, orattached to the outer nacelle 50 in any other suitable manner at theouter end 102.

Further, for the embodiment depicted, the plurality of part span inletguide vanes 100 extend generally along the radial direction R from theouter end 102 to an inner end 104 (i.e., an inner end 104 along theradial direction R). Moreover, as will be appreciated, for theembodiment depicted, each of the plurality of part span inlet guidevanes 100 are unconnected with an adjacent part span inlet guide vane100 at the respective inner ends 104 (i.e., adjacent part span inletguide vanes 100 do not contact one another at the radially inner ends104, and do not include any intermediate connection members at theradially inner ends 104, such as a connection ring, strut, etc.). Morespecifically, for the embodiment depicted, each part span inlet guidevane 100 is completely supported by a connection to the outer nacelle 50at the respective outer end 102 (and not through any structureextending, e.g., between adjacent part span inlet guide vanes 100 at alocation inward of the outer end 102 along the radial direction R). Aswill be discussed below, such may reduce an amount of turbulencegenerated by the part span inlet guide vanes 100.

Moreover, is depicted, each of the plurality of part span inlet guidevanes 100 do not extend completely between the outer nacelle 50 and,e.g., the hub 48 of the turbofan engine 10. More specifically, for theembodiment depicted, each of the plurality of inlet guide vane define aninlet guide vane (“IGV”) span 106 along the radial direction R, andfurther each of the plurality of part span inlet guide vanes 100 furtherdefine a leading edge 108 and a trailing edge 110. The IGV span 106refers to a measure along the radial direction R between the outer end102 and the inner end 104 of the part span inlet guide vane 100 at theleading edge 108 of the part span inlet guide vane 100. Similarly, itwill be appreciated, that the plurality of fan blades 40 of the fan 38define a fan blade span 112 along the radial direction R. Morespecifically, each of the plurality of fan blades 40 of the fan 38 alsodefines a leading edge 114 and a trailing edge 116, and the IGV span 106refers to a measure along the radial direction R between a radiallyouter tip and a base of the fan blade 40 at the leading edge 114 of therespective fan blade 40.

For the embodiment depicted, the IGV span 106 is at least about fivepercent of the fan blade span 112 and up to about fifty-five percent ofthe fan blade span 112. For example, in certain exemplary embodiments,the IGV span 106 may be between about fifteen percent of the fan bladespan 112 and about forty-five percent of the fan blade span 112, such asbetween about thirty percent of the fan blade span 112 and about fortypercent of the fan blade span 112.

Reference will now also be made to FIG. 3 , providing an axial view ofthe inlet 60 to the turbofan engine 10 of FIGS. 1 and 2 . As will beappreciated, for the embodiment depicted, the plurality of part spaninlet guide vanes 100 of the turbofan engine 10 includes a relativelylarge number of part span inlet guide vanes 100. More specifically, forthe embodiment depicted, the plurality of part span inlet guide vanes100 includes between about ten part span inlet guide vanes 100 and aboutfifty part span inlet guide vanes 100. More specifically, for theembodiment depicted, the plurality of part span inlet guide vanes 100includes between about twenty part span inlet guide vanes 100 and aboutforty-five part span inlet guide vanes 100, and more specifically,still, the embodiment depicted includes thirty-two part span inlet guidevanes 100. Additionally, for the embodiment depicted, each of theplurality of part span inlet guide vanes 100 are spaced substantiallyevenly along the circumferential direction C. More specifically, each ofthe plurality of part span inlet guide vanes 100 defines acircumferential spacing 118 with an adjacent part span inlet guide vane100, with the circumferential spacing 118 being substantially equalbetween each adjacent part span inlet guide vane 100.

Although not depicted, in certain exemplary embodiments, the number ofpart span inlet guide vanes 100 may be substantially equal to the numberof fan blades 40 of the fan 38 of the turbofan engine 10. In otherembodiments, however, the number of part span inlet guide vanes 100 maybe greater than the number of fan blades 40 of the fan 38 of theturbofan engine 10, or alternatively, may be less than the number of fanblades 40 of the fan 38 of the turbofan engine 10.

Further, it should be appreciated, that in other exemplary embodiments,the turbofan engine 10 may include any other suitable number of partspan inlet guide vanes 100 and/or circumferential spacing 118 of thepart span inlet guide vanes 100. For example, referring now briefly toFIG. 4 , an axial view of an inlet 60 to a turbofan engine 10 inaccordance with another exemplary embodiment of the present disclosureis provided. For the embodiment of FIG. 4 , the turbofan engine 10includes less than twenty part span inlet guide vanes 100. Morespecifically, for the embodiment of FIG. 4 , the turbofan engine 10includes at least eight part span inlet guide vanes 100, or morespecifically includes exactly eight part span inlet guide vanes 100.Additionally, for the embodiment of FIG. 4 , the plurality of part spaninlet guide vanes 100 are not substantially evenly spaced along thecircumferential direction C. For example, at least certain of theplurality of part span inlet guide vanes 100 define a firstcircumferential spacing 118A, while other of the plurality of part spaninlet guide vanes 100 define a second circumferential spacing 118B. Forthe embodiment depicted, the first circumferential spacing 118A is atleast about twenty percent greater than the second circumferentialspacing 118B, such as at least about twenty-five percent greater such asat least about thirty percent greater, such as up to about two hundredpercent greater. Notably, as will be described in greater detail below,the circumferential spacing 118 refers to a mean circumferential spacingbetween adjacent part span inlet guide vanes 100. The non-uniformcircumferential spacing may, e.g., offset structure upstream of the partspan inlet guide vanes 100.

Referring back to FIG. 2 , it will be appreciated that each of theplurality of part span inlet guide vanes 100 is configured to pre-swirlan airflow 58 provided through the inlet 60 of the outer nacelle 50,upstream of the plurality of fan blades 40 of the fan 38. As brieflydiscussed above, pre-swirling the airflow 58 provided through the inlet60 of the outer nacelle 50 prior to such airflow 58 reaching theplurality of fan blades 40 of the fan 38 may reduce separation lossesand/or shock losses, allowing the fan 38 to operate with the relativelyhigh fan tip speeds described above with less losses in efficiency.

As discussed, the present disclosure provides a means for directingincoming objects towards an outer portion of the turbofan engine 200 incommunication and/or on the inlet pre-swirl feature, e.g., configured asa plurality of part span inlet guide vanes 100, as described in greaterdetail herein. As described herein, the means for directing incomingobjects towards an outer portion of the turbofan engine 200 directsincoming objects away from the core air flowpath 37 and towards thebypass airflow passage 56. This provides a deflection mechanism thatfacilitates ingestion of an object into an outer portion of the turbofanengine 10 by minimizing the chance that the object travels to the coreof the turbofan engine 10.

Referring now generally to FIGS. 5 through 7 , in exemplary embodimentsof the present disclosure, the means for directing incoming objectstowards an outer portion of the turbofan engine 200 includes a shroud210 in communication with a portion of the inlet pre-swirl feature,e.g., configured as a plurality of part span inlet guide vanes 100.

The shroud 210 is configured to separate an engine inlet airflow, e.g.,the volume of air 58, into an inner airflow portion, e.g., a secondportion of the air indicated by arrows 64 that is directed or routedinto the core air flowpath 37, and an outer airflow portion, e.g., afirst portion of the air indicated by arrows 62 that is directed orrouted into the bypass airflow passage 56, relative to the radialdirection R.

In this manner, the means for directing incoming objects towards anouter portion of the turbofan engine 200 directs an incoming object 220away from the core air flowpath 37 and towards the bypass airflowpassage 56. The shroud 210 minimizes the potential for an incomingobject 220 that may strike an inlet guide vane 100 from being deflectedtoward the core air flowpath 37.

Referring to FIG. 5 , a close-up, cross-sectional view of a fan section14 and a forward end of a turbomachine 16 of a turbofan engine 10 inaccordance with an exemplary embodiment of the present disclosure isprovided. The exemplary turbofan engine 10 of FIG. 5 may be configuredin a similar manner as the exemplary engine of FIG. 2 described above.In the exemplary embodiment depicted, the shroud 210 is located at theinner end 104 of the inlet pre-swirl feature, e.g., configured as aplurality of part span inlet guide vanes 100. Reference will now also bemade to FIG. 6 , providing an axial view of the inlet 60 to the turbofanengine 10 of FIGS. 1 and 2 , which illustrates the shroud 210 extendingcircumferentially at the inner end 104 of each of the part span inletguide vanes 100.

Referring to FIG. 7 , a close-up, cross-sectional view of a fan section14 and a forward end of a turbomachine 16 of a turbofan engine 10 inaccordance with an exemplary embodiment of the present disclosure isprovided. The exemplary turbofan engine 10 of FIG. 7 may be configuredin a similar manner as the exemplary engine of FIG. 2 described above.In the exemplary embodiment depicted, the shroud 210 is located at aportion of the inlet pre-swirl feature, e.g., configured as a pluralityof part span inlet guide vanes 100, between the inner end 104 and theouter end 102. For example, in an exemplary embodiment, the shroud 210is located at a portion of the inlet pre-swirl feature, e.g., configuredas a plurality of part span inlet guide vanes 100, that is closer to theinner end 104 than the outer end 102.

In other exemplary embodiments, it is contemplated that the shroud 210may be located anywhere along the inlet pre-swirl feature, e.g.,configured as a plurality of part span inlet guide vanes 100, such thatit remains within the radially innermost 50% of the inlet guide vane100, e.g., at any portion that is closer to the inner end 104 than theouter end 102. It is also contemplated that the shroud 210 may belocated at a midpoint between the inner end 104 and the outer end 102.

Referring now to FIG. 8 , a close-up, cross-sectional view of a fansection 14 and a forward end of a turbomachine 16 of a turbofan engine10 in accordance with an exemplary embodiment of the present disclosureis provided. The exemplary turbofan engine 10 of FIG. 8 may beconfigured in a similar manner as the exemplary engine of FIG. 2described above. In an exemplary embodiment, the means for directingincoming objects towards an outer portion of the turbofan engine 200includes a leading edge 108 of the inlet pre-swirl feature, e.g.,configured as a plurality of part span inlet guide vanes 100, having aforward sweep angle 154.

For the exemplary embodiment depicted in FIG. 8 , the exemplary partspan inlet guide vanes 100 are configured as “forward swept” part spaninlet guide vanes. More specifically, as is depicted, the exemplary partspan inlet guide vanes 100 each define a longitudinal axis 150 extendinghalfway between the leading edge 108 and a trailing edge 110 from theradially inner end 104 to the radially outer end 102. Additionally, theexemplary turbofan engine 10 defines a reference plane 152, or morespecifically, the radial direction R and circumferential direction C theturbofan engine 10 together define a reference plane 152. Thelongitudinal axis 150 of each of the plurality of part span inlet guidevanes 100 intersects the reference plane 152 and defines a forward sweepangle 154 with the reference plane 152.

In an exemplary embodiment, the forward sweep angle 154 with thereference plane 152 is greater than about three degrees and up to aboutsixty-five degrees. In another exemplary embodiment, the forward sweepangle 154 with the reference plane 152 is between about three degreesand about forty-five degrees. In yet another exemplary embodiment, theforward sweep angle 154 with the reference plane 152 is between aboutthree degrees and about thirty degrees.

In this manner, a leading edge 108 of the inlet pre-swirl feature, e.g.,configured as a plurality of part span inlet guide vanes 100, having aforward sweep angle 154 directs incoming objects 220 away from the coreair flowpath 37 and towards the bypass airflow passage 56. This providesa deflection mechanism that facilitates ingestion of an object into anouter portion of the turbofan engine 10 by minimizing the chance thatthe object travels to the core of the turbofan engine 10.

Referring now to FIG. 9 , a close-up, cross-sectional view of a fansection 14 and a forward end of a turbomachine 16 of a turbofan engine10 in accordance with an exemplary embodiment of the present disclosureis provided. The exemplary turbofan engine 10 of FIG. 9 may beconfigured in a similar manner as the exemplary engine of FIG. 2described above. In an exemplary embodiment, the means for directingincoming objects towards an outer portion of the turbofan engine 200includes a leading edge 108 of the inlet pre-swirl feature, e.g.,configured as a plurality of part span inlet guide vanes 100, that isserrated. For example, the leading edge 108 includes a serrated portion230. As used herein, the term “serrated”, with reference to a leadingedge 108, refers to any shape or configuration that is able to slice anyincoming objects 220.

In this manner, a leading edge 108 of the inlet pre-swirl feature, e.g.,configured as a plurality of part span inlet guide vanes 100, having theserrated portion 230 slices and/or cuts any incoming objects 220 anddirects incoming objects 220 away from the core air flowpath 37 andtowards the bypass airflow passage 56. This provides a deflectionmechanism that facilitates ingestion of an object into an outer portionof the turbofan engine 10 by minimizing the chance that the objecttravels to the core of the turbofan engine 10.

Referring to FIG. 9 , in an exemplary embodiment, the means fordirecting incoming objects towards an outer portion of the turbofanengine 200 includes a leading edge 108 of the inlet pre-swirl feature,e.g., configured as a plurality of part span inlet guide vanes 100, thatincludes saw-toothed serrations 232.

Referring to FIG. 10 , in another exemplary embodiment, the means fordirecting incoming objects towards an outer portion of the turbofanengine 200 includes a leading edge 108 of the inlet pre-swirl feature,e.g., configured as a plurality of part span inlet guide vanes 100, thatincludes scalloped serrations 234.

It is also contemplated that any of the serrated portions 230 of theleading edge 108 of the inlet pre-swirl feature, e.g., configured as aplurality of part span inlet guide vanes 100, may also be acousticallytuned.

In other exemplary embodiments, the means for directing incoming objectstowards an outer portion of the turbofan engine 200 includes an inletpre-swirl feature, e.g., configured as a plurality of part span inletguide vanes 100, having a leading edge formed of a metallic material.For example, the inlet pre-swirl feature, e.g., configured as aplurality of part span inlet guide vanes 100, can be made of manydifferent materials, including polymer composites made of carbon fiber &resin, or fabricated from metal, including aluminum or stainless steelalloys. A composite or aluminum pre-swirl feature may incorporate ametallic leading edge made of titanium or stainless steel specificallyto provide stiffness and address the issue of bird ingestion.Incorporating additional stiffness into the pre-swirl feature design viainternal trusses or other structures should be well known to one that isskilled in the art, and can be accomplished by many different structuralmethods, depending on the chosen material and blade shape.

Further aspects of the disclosure are provided by the subject matter ofthe following clauses:

A turbofan engine comprising: a fan comprising a plurality of fanblades; a turbomachine operably coupled to the fan for driving the fan,the turbomachine comprising a compressor section, a combustion section,and a turbine section in serial flow order and together defining a coreair flowpath; a nacelle surrounding and at least partially enclosing thefan; an inlet pre-swirl feature located upstream of the plurality of fanblades, the inlet pre-swirl feature attached to or integrated into thenacelle; and a means for directing incoming objects towards an outerportion of the turbofan engine in communication with the inlet pre-swirlfeature.

The turbofan engine of any preceding clause, wherein the means fordirecting incoming objects towards the outer portion of the turbofanengine comprises a shroud in communication with a portion of the inletpre-swirl feature.

The turbofan engine of any preceding clause, wherein the shroud isconfigured to separate an engine inlet airflow into an inner airflowportion and an outer airflow portion relative to a radial direction.

The turbofan engine of any preceding clause, wherein the inlet pre-swirlfeature includes an outer end and an inner end relative to the radialdirection, and wherein the shroud is located at the inner end of theinlet pre-swirl feature.

The turbofan engine of any preceding clause, wherein the inlet pre-swirlfeature includes an outer end and an inner end relative to the radialdirection, and wherein the shroud is located at a portion of the inletpre-swirl feature that is closer to the inner end than the outer end.

The turbofan engine of any preceding clause, wherein the means fordirecting incoming objects towards the outer portion of the turbofanengine comprises a leading edge of the inlet pre-swirl feature having aforward sweep.

The turbofan engine of any preceding clause, wherein the forward sweepof the leading edge defines an angle between 3 degrees and 65 degrees.

The turbofan engine of any preceding clause, wherein the forward sweepof the leading edge defines an angle between 3 degrees and 45 degrees.

The turbofan engine of any preceding clause, wherein the forward sweepof the leading edge defines an angle between 3 degrees and 30 degrees.

The turbofan engine of any preceding clause, wherein the means fordirecting incoming objects towards the outer portion of the turbofanengine comprises a leading edge of the inlet pre-swirl feature that isserrated.

The turbofan engine of any preceding clause, wherein the leading edge ofthe inlet pre-swirl feature includes scalloped serrations.

The turbofan engine of any preceding clause, wherein the leading edge ofthe inlet pre-swirl feature includes saw-toothed serrations.

The turbofan engine of any preceding clause, wherein the leading edge ofthe inlet pre-swirl feature includes acoustically tuned serrations.

The turbofan engine of any preceding clause, wherein the means fordirecting incoming objects towards the outer portion of the turbofanengine comprises the inlet pre-swirl feature having a leading edgeformed of a metallic material.

A turbofan engine comprising: a fan comprising a plurality of fanblades; a turbomachine operably coupled to the fan for driving the fan,the turbomachine comprising a compressor section, a combustion section,and a turbine section in serial flow order and together defining a coreair flowpath; a nacelle surrounding and at least partially enclosing thefan; an inlet pre-swirl feature located upstream of the plurality of fanblades, the inlet pre-swirl feature attached to or integrated into thenacelle; and a shroud in communication with a portion of the inletpre-swirl feature and configured to separate an engine inlet airflowinto an inner airflow portion and an outer airflow portion relative to aradial direction.

The turbofan engine of any preceding clause, wherein the inlet pre-swirlfeature includes an outer end and an inner end relative to the radialdirection, and wherein the shroud is located at the inner end of theinlet pre-swirl feature.

The turbofan engine of any preceding clause, wherein the inlet pre-swirlfeature includes an outer end and an inner end relative to the radialdirection, and wherein the shroud is located at a portion of the inletpre-swirl feature that is closer to the inner end than the outer end.

The turbofan engine of any preceding clause, wherein the shroud isfurther configured to direct incoming objects towards an outer portionof the turbofan engine.

The turbofan engine of any preceding clause, wherein the inlet pre-swirlfeature is one of a plurality of inlet pre-swirl features, wherein theshroud extends along a circumferential direction between the pluralityof inlet pre-swirl features.

The turbofan engine of any preceding clause, wherein the shroud extendssubstantially 360 degrees in the circumferential direction.

This written description uses examples to disclose the disclosure,including the best mode, and also to enable any person skilled in theart to practice the disclosure, including making and using any devicesor systems and performing any incorporated methods. The patentable scopeof the disclosure is defined by the claims, and may include otherexamples that occur to those skilled in the art. Such other examples areintended to be within the scope of the claims if they include structuralelements that do not differ from the literal language of the claims, orif they include equivalent structural elements with insubstantialdifferences from the literal languages of the claims.

While this disclosure has been described as having exemplary designs,the present disclosure can be further modified within the scope of thisdisclosure. This application is therefore intended to cover anyvariations, uses, or adaptations of the disclosure using its generalprinciples. Further, this application is intended to cover suchdepartures from the present disclosure as come within known or customarypractice in the art to which this disclosure pertains and which fallwithin the limits of the appended claims.

What is claimed is:
 1. A turbofan engine comprising: a fan comprising aplurality of fan blades; a turbomachine operably coupled to the fan fordriving the fan, the turbomachine comprising a compressor section, acombustion section, and a turbine section in serial flow order andtogether defining a core air flowpath; a nacelle surrounding and atleast partially enclosing the fan; an inlet pre-swirl feature locatedupstream of the plurality of fan blades, the inlet pre-swirl featureattached to or integrated into the nacelle; and a means for directingincoming objects towards an outer portion of the turbofan engine incommunication with the inlet pre-swirl feature.
 2. The turbofan engineof claim 1, wherein the means for directing incoming objects towards theouter portion of the turbofan engine comprises a shroud in communicationwith a portion of the inlet pre-swirl feature.
 3. The turbofan engine ofclaim 2, wherein the shroud is configured to separate an engine inletairflow into an inner airflow portion and an outer airflow portionrelative to a radial direction.
 4. The turbofan engine of claim 3,wherein the inlet pre-swirl feature includes an outer end and an innerend relative to the radial direction, and wherein the shroud is locatedat the inner end of the inlet pre-swirl feature.
 5. The turbofan engineof claim 3, wherein the inlet pre-swirl feature includes an outer endand an inner end relative to the radial direction, and wherein theshroud is located at a portion of the inlet pre-swirl feature that iscloser to the inner end than the outer end.
 6. The turbofan engine ofclaim 1, wherein the means for directing incoming objects towards theouter portion of the turbofan engine comprises a leading edge of theinlet pre-swirl feature having a forward sweep.
 7. The turbofan engineof claim 6, wherein the forward sweep of the leading edge defines anangle between 3 degrees and 65 degrees.
 8. The turbofan engine of claim6, wherein the forward sweep of the leading edge defines an anglebetween 3 degrees and 45 degrees.
 9. The turbofan engine of claim 6,wherein the forward sweep of the leading edge defines an angle between 3degrees and 30 degrees.
 10. The turbofan engine of claim 1, wherein themeans for directing incoming objects towards the outer portion of theturbofan engine comprises a leading edge of the inlet pre-swirl featurethat is serrated.
 11. The turbofan engine of claim 10, wherein theleading edge of the inlet pre-swirl feature includes scallopedserrations.
 12. The turbofan engine of claim 10, wherein the leadingedge of the inlet pre-swirl feature includes saw-toothed serrations. 13.The turbofan engine of claim 10, wherein the leading edge of the inletpre-swirl feature includes acoustically tuned serrations.
 14. Theturbofan engine of claim 1, wherein the means for directing incomingobjects towards the outer portion of the turbofan engine comprises theinlet pre-swirl feature having a leading edge formed of a metallicmaterial.
 15. A turbofan engine comprising: a fan comprising a pluralityof fan blades; a turbomachine operably coupled to the fan for drivingthe fan, the turbomachine comprising a compressor section, a combustionsection, and a turbine section in serial flow order and togetherdefining a core air flowpath; a nacelle surrounding and at leastpartially enclosing the fan; an inlet pre-swirl feature located upstreamof the plurality of fan blades, the inlet pre-swirl feature attached toor integrated into the nacelle; and a shroud in communication with aportion of the inlet pre-swirl feature and configured to separate anengine inlet airflow into an inner airflow portion and an outer airflowportion relative to a radial direction.
 16. The turbofan engine of claim15, wherein the inlet pre-swirl feature includes an outer end and aninner end relative to the radial direction, and wherein the shroud islocated at the inner end of the inlet pre-swirl feature.
 17. Theturbofan engine of claim 15, wherein the inlet pre-swirl featureincludes an outer end and an inner end relative to the radial direction,and wherein the shroud is located at a portion of the inlet pre-swirlfeature that is closer to the inner end than the outer end.
 18. Theturbofan engine of claim 15, wherein the shroud is further configured todirect incoming objects towards an outer portion of the turbofan engine.19. The turbofan engine of claim 15, wherein the inlet pre-swirl featureis one of a plurality of inlet pre-swirl features, wherein the shroudextends along a circumferential direction between the plurality of inletpre-swirl features.
 20. The turbofan engine of claim 19, wherein theshroud extends substantially 360 degrees in the circumferentialdirection.